86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



(P.U. No. 16175) and was found at about the same level in the 

 Knight but in the patch of Badlands forming the saddle to the north 

 of Fossil Butte. Also the second of the two jaws from Knight Station, 

 earlier referred to as Diacodexisl sp. (1952, p. 72), since located in 

 the American Museum collections and found to be of Hexacodus, 

 evidently represents the larger H. uintensis. The specimen (A.M. No. 

 12844) includes M2 and M3 and is seen to correspond closely in the 

 form of M2 to the type. The other specimen, A.M. No. 12843, from 

 Knight Station, as discussed in the preceding section, appears to be of 

 Hexacodus pelodes. 



A careful search of Gray Bull materials from the Bighorn Basin in 

 both the American Museum and National Museum collections has 

 turned up only one specimen of Hexacodus among materials labeled 

 Diacodexis. The specimen (A.M. No. 4140) is a lower jaw with M2 

 and M3 and resembles most closely Hexacodus uintensis in the relative 

 proportions of the lower molar trigonids. It is interesting to note that 

 this was the specimen selected by Osborn to typify Trigonolestes 

 {■=■ Diacodexis) metsiacus in his "Evolution of Mammalian Molar 

 Teeth" (1907, p. 171, fig. 152B). Hexacodus is evidently very rare 

 in the Gray Bull horizon and so far has not been observed in this level 

 of the Knight. It has not been found, or at least not recognized, in any 

 of the horizons of the Wind River Basin, or the higher levels of the 

 Bighorn Wasatchian. 



REFERENCES 



Bradley, Wilmot H. 



1959. Revision of stratigraphic nomenclature of Green River formation of 

 Wyoming. Bull. Amer. Assoc. Petrol. Geol., vol. 43, No. 5, pp. 

 1072-1075. 

 Cope, Edward D. 



1872. On the dentition of Metalophodon. Proc. Amer. Philos. Soc, vol. 12, 



pp. 542-545. 



1873. On the new perissodactyles from the Bridger Eocene. Proc. Amer. 



Philos. Soc, vol. 13, pp. 35-36. 

 1877. Report upon the extinct Vertebrata obtained in New Mexico by 



parties of the expedition of 1S74. Rep. U. S. Geogr. Surv. West 



of looth Meridian (Wheeler), vol. 4, pt. 2, pp. i-iv, 1-370, pis. 22-83. 

 1884. The Vertebrata of the Tertiary formations of the West. Book i. 



Rep. U. S. Geol. Surv. Terr. (Hayden), vol. 3, pp. i-xxxiv, 1-1009, 



figs. 1-38, pis. I -75a. 

 Denison, Robert H. 



1938. The broad-skulled pseudocreodi. Ann. New York Acad. Sci., vol. 27, 



art. 3, pp. 163-256, figs. 1-32. 



